I just went running up a hill with a gigantic set of keys in one
pocket
and an iPhone and harmonica in the other. On the way up the hill I
found that I could maintain a rhythm that kept the pockets
adaptively and widely flapping back and forth and that the overall
effect was one of energy storage.
Add stiffer pockets and shaped
and weighted exercise gyros with further foam wings extended
and you are well on your way to looking rediculous if not
eventually
human powered flight.